OKHA, Russia -- A faulty stove is believed to be responsible for the deaths of five people Thursday on Sakhalin Island in Russia's Pacific border region.

The dead were found in two apartments in a building in the town of Okha, Itar-Tass reported. A married couple, both age 49, were in one apartment and a 64-year-old woman and two children were in the other.

"Supposedly, they all died at night," an emergency official said. "An investigation is under way. A preliminary version is a faulty gas stove and carbon monoxide poisoning. There was no fire in the house."